How do you handle uncomfortable questions during a wedding reception?

Q: I'm getting married in December and buying a house from a relative in November. Since my reception is being held at my new home, it occurred to me that I need to come up with a reply when asked how it was I got this home. I'm buying the home from my last surviving great-uncle (in his late 90s) who has outlived 2 wives and his 3 children. His grandchildren never call, never visit and frankly, probably wouldn't know he was even alive if he didn't send Christmas cards. He and his current wife (she's just over 80) are moving into an assisted living apartment and I'm getting the house for well below market value as he has no desire to leave anything to his grandchildren. At least 2 attendees are in contact with these grandchildren and when asked about the house, I want to completely avoid anything getting back to these folks so that they don't make the lives of this elderly couple miserable. I just need ideas on what to say to immediately end any discussion on the matter without being rude about it. I should add that my normal response is "I'm sorry, but could we talk about something else?" It is unlikely that the grandchildren will know about the property transfer prior to the wedding. I really appreciate the comments! In answer to some comments, I don't care 2 bits about the feelings of his grandchildren. I just think our transaction is private business and hoped with a 'gentle' response that it will eliminate further questions. I've noticed that my older relatives hold on to topics like a dog with a bone. My mom thinks my standard answer is rude itself, so that's why I asked.

A: Say, "We liked this house, so we bought it." and change the subject. They will hopefully get the hint. Congratulations on your marriage! I hope that you and your partner have many wonderful years to come.

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